(a) Field of the Invention
The present invention relates to a beamforming apparatus and method for expanding coverage of a control channel in a wireless communication system.
(b) Description of the Related Art
Communication devices for a variety of wireless communication networks such as cellular networks, mesh networks, and ad hoc networks use control channels which are allocated to transmit (or broadcast) various types of control messages and reference signals. In this case, control messages or the like may be used for link control, access control, or network control in a communication network. Control channels may be allocated in advance or when necessary. In order to form a communication link and network with a neighboring communication device, each communication device needs to successfully receive a reference signal and a control message, which are transmitted from the neighboring communication device over a control channel. Thus, the coverage of the communication link can be limited by the coverage of the control channel.
By employing a beamforming technique on a control message or the like with the use of multiple antennas or sector antennas, the coverage of a control channel can be expanded without increasing transmission power. However, this may result in coverage holes.
To avoid coverage holes, as many control messages as the required number of beams are transmitted to all the communication devices included within coverage, which may result in higher overhead and a lower transmission rate.